The subject matter of the present invention is in a sealing composition made from clay minerals, fillers, binding agents and water, with which permeable soils, e.g., sandy soils, can be sealed. The sealing compositions according to the invention can be put into the ground by known construction methods in the form of vertical barrier walls, horizontal barriers, e.g., bottom barriers, dump linings, dump covers, etc. The main purpose of these sealing compositions is to prevent the propagation, diffusion or spreading of soil contaminants and especially the penetration of pollutants into the ground water. The immobilization of pollutants can be improved in some cases by filling dump excavations with the sealing composition.
The use soil barriers against the spread of pollutants, such as dump seepage etc., is known in the art. Usually, the soil barriers are in the form of a pair of trench walls made by different methods and of different sealing compositions. These known techniques include the One-Phase Trench Wall and the Two-Phase Trench Wall.
In the One-Phase Trench Wall technique the soil barrier is formed of a composition which contains about 2 to 4 wt.-% sodium bentonite, 12.5 to 20 wt.-% cement, and 75 to 85 wt.-% water. The Two-Phase Trench Wall (Backfill Method) employs a composition which contains about 0.2 to 2 wt.-% sodium bentonite, 60 to 75 wt.-% soil (waste from trench), and 25 to 35 wt.-% water.
A one-phase composition has a low solids content of about 15 to 25 wt.-%. Accordingly, the one-phase composition has the disadvantage of a relatively high permeability, k (for water)=10.sup.-7 to 10.sup.-8 m/s, and the danger of erosion. When the two components cement and bentonite, which are sensitive to chemicals, are in contact with pollutants, long-lasting, adequate protection of ground water is especially doubtful.
The two-phase composition has a higher solids content and a lower permeability (k=approximately 10.sup.-9 m/s). However, the permeability clearly can vary if there are relatively great differences in the composition of the excavated and back-filled soil. This composition remains permanently soft since it does not contain cement or any other binding agent. As such, there is a danger of erosion at points where the wall is adjacent to coarse loose rock or gravel. The resistance of these compositions to pollutants is unpredictable since their make-up differs from case to case, and has to be determined by individualized time consuming tests.
In view of the prior art disadvantages, bearing in mind that maximum reliability against pollutants is precisely what is expected of soil barriers, it is an object of the present invention to provide a sealing composition which will not have the above-discussed disadvantages, and which can be made and handled in a simple manner with conventional construction apparatus.